Two-chamber clearance unloader



Feb. 8, 1927.

- 1,616,988 I s. B. REDFIELD TIP-CHAIBBR CLEARANCE UNLOADER I F'iied Aug. 4 1925 2 Sheets-Sheet 1 IN V EN TOR.

(Shana/Jen BReaQZeIJ.

HIS ATTOR EY.

Feb. -8 1927.

- 1,616,988 S. B. REDFIELD TWO-CHAMBER CLEARANCE UNLOADER Filed Aug. 4.

IN V EN TOR.

Show 01212301 73143 I BY%{ -H /s ATTONEY- Patented Feb. 8, 1927.

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Application filed-August 4, 192a. Serial N e/127,062.

This inventionrelates to compressors, but more particularly to a clearance unloader having a plurality of clearance chambers, in this instance two chambers being pro vided, both for the same end of the cylinder. The objects of the invention are to enable a multiplicity of unloading steps to be obtained by means of two clearance chambers at one end of the cylinder, and one or more inlet valves at the opposite end of the cylinder having valve openers. 'By operating the clearance valves and the valve opener or.

dinal sectional elevation, and

openers in proper predetermined order, the

' desirednumber of steps of unloading is obtained V The invention is shown in onesuitable form in the accompanying drawings, in which T Figural is a diagrammatic representation of an unloading system partly in longitu- Figure 2 is a similar view of a tionl, V

Referring to the drawings, the cylinder A is provided with a piston B, and the air drawn from the intake "0 is discharged through the dischargevpipe D to the receiv-er E inthe usual manner.

The cylinderis provided with the usual inlet'and discharge'valves F and G, which maybe plate valves of any suitable type, and one end of the cylinder is provided with two clearance chambers H and J having clearance valves K and L while one of'the inlet mo dificavalves at the opposite end of the cylinder,

as for instance the inlet valve designated by O, is provided w th'a valve opener. regulator P respons ve to receiver pressure through the pipe Q is connected to operate the two clearance valves K and L and the valve opener of the valve 0 in predeterminedorder, to eiiect the desired steps, of unloading. v

'The clearance valve L has a piston R in the cylinder S and pressure fluid is supplied underneath the piston through the pipe 1 to open the valve which is maintained closed by the spring T; a vent U vents one end of the cylinder. The clearance valve K is provided with a piston :R in the cylinder V and pressure fluid is supplied underneath the piston R from the pipe 2. i T

In the operation of the device, the clearance valve K is intended to be opened and then closed and reopened in the cycle Of operations, so that the cylinder V is provided with the additional vent 1 and when pressure is cut oli fromthe pipe 2 the valve K is rapidly closed by the'spring T due to leakage of pressure through the vent WV.

The inlet valve O is provided with the valve opener of any suitable type, in this instance, fingers X. being connected tothe piston rod of the piston Y. AspringZ normally retracts the fingers X and pressure fluid is supplied behind the piston Y through the pipe 3 for opening the valve and holding 1t open.

In the cycle of operations contro-lledby the regulator P, the clearance valve L is first opened to reduce the load by one-quarter. The clearance valve K is next opened for i the same .endofthecylinde'r to produce half load while maintaining the clearance valve L open. The clearance valve K is then closed andthe inlet valve 0 at the opposite end of the cylinder is opened to produce onequarter load, and finally the clearance valve K isreo-pened to produce no load; By means ofthissimple system of unloading, live steps of unloading and, loading may be. produced by means of two clearance chambers for one end of the cylinder and an inlet valve opener or openers ,for the opposite end of the 'cyl V inder. t

The regulator P is shown diagrammatically and maybe of any suitable type, in this instance, the piston 00 controls the ports I), c, d and 6 connected respectivelyto the pipes 1, 2 and 3 since the ports d and e; are connected to each other. 1 The piston 42 is A provided with the port f and the groove 9 cooperating with the port I) to'continuously supply pressure to the cylinder of the clear anfce valve L so that said valve when once opened is maintained'opened through one c mplete cycle ofiunloading. The ports h and jconnected by the passage Z0 in the piston a are in a different angular plane from the port f and groove 9 and the piston is guided and prevented from rotating by means of the key or feather 0:. The end of thecylinder opposite to that at which pressure is introduced is provided with the vent p and an adjustable spring g serves 7 to returnthe piston.

In the operation of the apparatus, let it he assumed that the compressor is running any l a e a h an incr s Q r sure in the receiverhas moved the piston to V of the piston will next fall opposite the port in the regulator cylinder and pressure fluid will be supplied through the pipe 2 to open the clearance valve K and produce half load. In the neXt step of unloading the port it ar rives opposite the port (Z which opens/the inlet valve 0 at the opposite end of the cylinder, but pressure fluid is cut ofifltrom the pipe 2 causing the clearance valve K toclose final step of unloading the port it cooperates with the port 0 to maintain the inletvalve 0 open while the port in the pistonagain supplies. pressure through the port 0 and pipe/2 to cause the reopening ofthe clearance valve K, thus wholly unloading the compr-essor.

Obviously, if the step of one-quarter load is not desired for any reason, as being unnecessary, that step may be omitted in which case the cycle of operations would produce three-quarters load, half load and no load. In such case the clearance valve L would first he opened and maintained open to produce one-quarter load, then the'clearance valve K would be opened and maintained opened to produce halt load, and finally the inlet valve 0 would be opened to produce no load.

In the modification of the apparatus shown in Figure 2, the first three steps of unloading, that is, three-quarters load, one-half load, and one-quarter load are carried out in the same manner as illustrated and described in connection with Figure 1, but the final step to produce no load is eiiected, not by reopening the clearance valve K, but by holding open the inlet valve 0 at the clearance end of the cylinder, otherwise, the sys- I tem of operation is the same. In Figure 2 the clearance chamber H corresponds to the clearance chamber in Figure 1, but for convenience is located in the head of the cylinder. The inlet valve 0 at the clearance end ofthe cylinder is provided with a valve opener similar in. all respects to the valve opener for the inlet valve O at, the opposite end of the-cylinder. The pipe 4 for the inlet valve 0' leads to the port 5 in the regu lator cylinder and the port j shown in Figure 1 in the regulator piston a is omitted from the piston 0; of the regulator P in Figure 2 and replaced by the port 6. The first three steps of unloading in the operation of the regulator P in Figure 2 are similar to those described ,1n COlll'lBCtlOIhWltll Figure 1 For the last step, however, the clearance valve K in Figure 2 as-stated remains closed and when the port it in the piston a registers with the port 5 for the last step of unloading, the inlet valve 0, is opened and since the inlet valve 0 at the opposite end of the cylinder is maintained opened because port 6 registers with port 6, the-cylinder is wholly unloaded.

I claim: 7

1. In a compressor unloader, the combination of a cylinder and piston, inlet and dis charge valves, a receiver, two clearance chambers for one end of the cylinder, clearance valves for said chambers, means for holding open. one of the inlet valves for the opposite end of the cylinder, and fluid actuated means responsive to receiver pressure for actuating said clearance valves and said inlet valve opener to unload and load the compressor in steps. 1 I

2. In a compressor unl-oader, the combination of a cylinder and piston, inlet and discharge valves, a recelver, two clearance chambers for one end of the cylinder, clearance valves for said chambers, means for holding open one of the inlet valves for the opposite end of the cylinder, and fluid actuated means responsive to receiver pressure:

for unloading the compressor by first holding open one clearance valve, then opening the other clearance valve, then closing one clearance valve and holding the said inlet valve open and finally wholly unloading the compressor. 7 v

3. In a con'lprcssor iniloader, the combina tion of a cylinder'and piston, inlet and discharge valves, a receiver, two clearance chambers for one end of the cylinder, clearance valves for said chambers, means for holding open one of the inlet valves for the opposite end of the cylinder, and fluid actuated means responsive to receiver pressure for unloading the compressor by first holding open one clearance valve, then opening the other clearance valve, then closing one clearance valve and holding the said inlet valve open and finally wholly unloading the compressor by reopening the said clearance valve which had been previously closed.

4. In a compressor unloader, the combination of a cylinder and piston, inlet and discharge valves, a receiver, two clearance chambers for one end of the cylinder, clearance valves for said chambers, means for holding open an inlet valve at each end of the cylinder, and fluid actuated means responsive to receiver pressure for actuating; said clearance valves and said inlet'valve openers to unload and load the compressor 1n steps.

In testimony whereof I have'signed this specification. r

SNOWDEN 1 RED} 1111141), 

